This invention relates to the production of continuous glass fibers, e.g., fibers made by melting particulate batch ingredients or minerals, including basalt and the like, and, more particularly, to a method and apparatus for detecting a break in such fibers during the drawing process.
It is intended that the term "scattered," as used herein, denotes forward scattering, backscattering and right angle scattering of the incident radiation.
It is well known in the art that continuous glass fibers can be produced by attenuating a plurality of streams of molten glass into fibers, collecting the fibers into a strand and winding the strand into a package for subsequent use in manufacturing various products. The molten glass flows from a furnace and through a forehearth into a feeder or bushing which has a plurality of orifices formed therein. The molten glass flows from the orifices as streams which are pulled downwardly at a high rate of speed for attenuation into fibers. A plurality of the attenuated fibers are then gathered together into a strand, coated with a sizing and wound onto a collection tube on a winder collet.
During the fiber forming process, a fiber may break and cause a bead of molten glass to form on the undersurface of the bushing at the orifice at which the breakage occurred. Gradually, the bead of molten glass becomes larger and heavier; the increased weight causes it to fall and contact adjacent fibers which causes them to break. If the spacing between the adjacent orifices is extremely small, the bead of molten glass contacts the adjacent forming cone of molten glass, thus causing more fibers to break. If such breakage is not detected, additional fibers will be broken as the bead continues to grow; this breakage will continue until all of the fibers in the fan are broken. The time required to restart the fiber forming process is related to the number of fibers that have broken. Accordingly, a breakage must be detected as early as possible so that suitable corrective measures can be taken to minimize the downtime of the process.
Therefore, it is an object of this invention to provide a reliable method of and apparatus for detecting breakages in glass fibers during the fiber producing process.